Retraction Note to: Ambient air pollution and adverse birth outcomes: a systematic review and meta-analysis.

Retraction Note to: J Zhejiang Univ-Sci B (Biomed & Biotechnol) 2019 20(3):238-252. https://doi.org/10.1631/jzus.B1800122. The authors have retracted this article (Guo et al., 2019) because some data from the original literature had not been converted to appropriate units in the paper, which resulted in deviation of the meta-analysis results. For example, for the forest plot used to examine associations between PM exposure and the risk of adverse birth outcomes, the estimates from Brauer et al. (2008), Pedersen et al. (2013), Zhao et al. (2015), and Hansen et al. (2006) were on the originally reported scales of 1 µg/m, 10 µg/m, 10 µg/m, and Inter Quartile Range, respectively. None of these estimates had been converted to 20 µg/m increase scale that was stated in the article. Similar problem exists in the analysis on associations between NO exposure and risk of adverse birth outcomes. Therefore, the results of the meta-analysis are misleading. All authors have agreed to this retraction and express their deepest apologies to the original authors, publishers, and readers.